Old firmware versions (below V.06.00.00) connect to the server with direct VPN tunnels and use port 15000, new firmware versions (V.06.00.00 and above) connect with MQTT (SSL) connection and use port 15009.
If our router has V.06.00.00 or higher firmware version router must connect to RMS through port 15009!
If our router has lower than V.06.00.00 firmware version router must connect to RMS through port 15000!